What are the steps in data preparation? Are there specific steps we need to take for specific problems? The answer is not that straightforward: Practice and knowledge will design the best recipe for each case. First, there are two types of data preparation: KPI calculation to extract the information from the raw data and data preparation for the data science algorithm. While the first one is domain and business dependent, the second one is more standardized.

A successful data scientist understands a wide range of Machine Learning algorithms and can explain the results to stakeholders. But, unfortunately, not every stakeholder has a sufficient amount of training to grasp the complexities of ML. Luckily, we can aid our explanations by using dimensionality reduction techniques to create visual representations of high dimensional data. This article will take you through one such technique called t-Distributed Stochastic Neighbor Embedding (t-SNE). Perfect categorization of Machine Learning techniques is not always possible due to the flexibility demonstrated by specific algorithms, making them useful when solving different problems (e.g., one can use k-NN for regression and classification).

In the last blog we saw about basics of Gradient Descent and how it works.This time we will see math behind it. We are actually subtracting some part from value of parameter and updating it.We keep doing this until we get optimized value of parameter so the cost is minimum. You may be thinking that why '-' sign is used in above equation. If you look at image below, in the right side of curve slope is positive so by subtracting value from theta, we are actually getting closer to the optimal value, while on the left side the slope is negative so we are actually adding some part in value of theta and so getting closer to the optimal value. We keep updating value of theta until the change in value 0.001 (values may vary according to case).Usually we take value of learning rate as 0.01

Classification as a supervised learning concept is an important content in machine learning. It aims at categorizing a set of data into classes. There are several commonly-used classification methods nowadays such as k-nearest neighbors, random forest, and support vector machine. Each of them has its own pros and cons, and none of them is invincible for all kinds of problems. In this thesis, we focus on Quadratic Multiform Separation (QMS), a classification method recently proposed by Michael Fan et al. (2019). Its fresh concept, rich mathematical structure, and innovative definition of loss function set it apart from the existing classification methods. Inspired by QMS, we propose utilizing a gradient-based optimization method, Adam, to obtain a classifier that minimizes the QMS-specific loss function. In addition, we provide suggestions regarding model tuning through explorations of the relationships between hyperparameters and accuracies. Our empirical result shows that QMS performs as good as most classification methods in terms of accuracy. Its superior performance almost comparable to those of gradient boosting algorithms that win massive machine learning competitions.

The term "optimization" refers to the process of iteratively training a model to produce a maximum and minimum function evaluation to get a minimum cost function. It is crucial since it will assist us in obtaining a model with the least amount of error (as there will be discrepancies between the actual and predicted values). There are various optimization methods; in this article, we'll look at gradient descent and its three forms: batch, stochastic, and mini-batch. Note: Hyperparameter optimization is required to fine-tune the model. Before you begin training the model, you must first specify hyperparameters.

Support vector machines are a class of techniques in data science, which had great popularity in the data science community. They are mainly used in classification tasks and perform really well when few training data is available.

Numerous methods can build predictive models from software data. However, what methods and conclusions should we endorse as we move from analytics in-the-small (dealing with a handful of projects) to analytics in-the-large (dealing with hundreds of projects)? To answer this question, we recheck prior small-scale results (about process versus product metrics for defect prediction and the granularity of metrics) using 722,471 commits from 700 Github projects. We find that some analytics in-the-small conclusions still hold when scaling up to analytics in-the-large. For example, like prior work, we see that process metrics are better predictors for defects than product metrics (best process/product-based learners respectively achieve recalls of 98\%/44\% and AUCs of 95\%/54\%, median values). That said, we warn that it is unwise to trust metric importance results from analytics in-the-small studies since those change dramatically when moving to analytics in-the-large. Also, when reasoning in-the-large about hundreds of projects, it is better to use predictions from multiple models (since single model predictions can become confused and exhibit a high variance).

The quality of sleep has a deep impact on people's physical and mental health. People with insufficient sleep are more likely to report physical and mental distress, activity limitation, anxiety, and pain. Moreover, in the past few years, there has been an explosion of applications and devices for activity monitoring and health tracking. Signals collected from these wearable devices can be used to study and improve sleep quality. In this paper, we utilize the relationship between physical activity and sleep quality to find ways of assisting people improve their sleep using machine learning techniques. People usually have several behavior modes that their bio-functions can be divided into. Performing time series clustering on activity data, we find cluster centers that would correlate to the most evident behavior modes for a specific subject. Activity recipes are then generated for good sleep quality for each behavior mode within each cluster. These activity recipes are supplied to an activity recommendation engine for suggesting a mix of relaxed to intense activities to subjects during their daily routines. The recommendations are further personalized based on the subjects' lifestyle constraints, i.e. their age, gender, body mass index (BMI), resting heart rate, etc, with the objective of the recommendation being the improvement of that night's quality of sleep. This would in turn serve a longer-term health objective, like lowering heart rate, improving the overall quality of sleep, etc.

Active learning is a subfield of machine learning that focuses on improving the data collection efficiency of expensive-to-evaluate systems. Especially, active learning integrated surrogate modeling has shown remarkable performance in computationally demanding engineering systems. However, the existence of heterogeneity in underlying systems may adversely affect the performance of active learning. In order to improve the learning efficiency under this regime, we propose the partitioned active learning that seeks the most informative design points for partitioned Gaussian process modeling of heterogeneous systems. The proposed active learning consists of two systematic subsequent steps: the global searching scheme accelerates the exploration of active learning by investigating the most uncertain design space, and the local searching exploits the circumscribed information induced by the local GP. We also propose Cholesky update driven numerical remedies for our active learning to address the computational complexity challenge. The proposed method is applied to numerical simulations and two real-world case studies about (i) the cost-efficient automatic fuselage shape control in aerospace manufacturing; and (ii) the optimal design of tribocorrosion-resistant alloys in materials science. The results show that our approach outperforms benchmark methods with respect to prediction accuracy and computational efficiency.

The catastrophic forgetting of previously learnt classes is one of the main obstacles to the successful development of a reliable and accurate generative continual learning model. When learning new classes, the internal representation of previously learnt ones can often be overwritten, resulting in the model's "memory" of earlier classes being lost over time. Recent developments in neuroscience have uncovered a method through which the brain avoids its own form of memory interference. Applying a targeted exaggeration of the differences between features of similar, yet competing memories, the brain can more easily distinguish and recall them. In this paper, the application of such exaggeration, via the repulsion of replayed samples belonging to competing classes, is explored. Through the development of a 'reconstruction repulsion' loss, this paper presents a new state-of-the-art performance on the classification of early classes in the class-incremental learning dataset CIFAR100.